1. Field
One or more embodiments of the present invention relate to a three-dimensional (3D) ultrasonic probe.
2. Description of the Related Art
Examples of representative medical ultrasonic devices may include a diagnostic ultrasound imaging device that is mainly used to contrast an organ or a fetus in a human body. A diagnostic ultrasound imaging device has advantages in that the diagnostic ultrasound imaging device may contrast a specific point in a human body desired to be seen by a doctor who makes a diagnosis by enabling the doctor to arbitrarily adjust a radiation angle of ultrasound, unlike other medical devices for contrasting internal body structures such as an X-ray device, a computed tomography (CT) device, or a magnetic resonance imaging (MRI) device, and the diagnostic ultrasound imaging device has no radiation risks and may obtain an image in a shorter time than that of the other medical devices.
In order to obtain an image, a diagnostic ultrasound imaging device needs an ultrasonic probe or an ultrasonic transducer that is a unit and/or a device for converting an ultrasound signal into an electrical signal or an electrical signal into an ultrasound signal. The ultrasonic probe generally includes an ultrasonic module that includes a piezoelectric layer that converts an electrical signal into a sound signal or a sound signal into an electrical signal when a piezoelectric material vibrates, a matching layer that reduces an acoustic impendence difference between the piezoelectric layer and a human body in order for ultrasound that is generated in the piezoelectric layer to be transmitted to a target point of the human body as much as possible, a lens layer that focuses the ultrasound that travels to the front of the piezoelectric layer on a specific point, and a sound-absorbing layer that prevents image distortion by preventing the ultrasound from traveling to the back of the piezoelectric layer. Although the ultrasonic probe may include a single ultrasonic transducer when being used for special purposes, the ultrasonic probe generally includes a plurality of ultrasonic transducers when being used for medical purposes.
Ultrasonic probes for medical purposes may be classified according to the number of ultrasonic transducers, an arrangement method of ultrasonic transducers, a shape of an array axis of ultrasonic transducers, or an application field. When classified according to the number of ultrasonic transducers, ultrasonic probes for medical purposes may be classified into single transducer type ultrasonic probes and multi-transducer type ultrasonic probes. In this case, multi-transducer type ultrasonic probes may be classified according to an array method of ultrasonic transducers into one-dimensional (1D) array ultrasonic probes in which ultrasonic transducers are arranged on a single axis and two-dimensional (2D) array ultrasonic probes in which ultrasonic transducers are arranged on a plurality of axes that intersect each other. 1D array ultrasonic transducers may be classified according to a shape of an array axis of ultrasonic transducers into linear array ultrasonic probes and curvilinear array ultrasonic probes.
1D array ultrasonic transducers that are the most often used may obtain only a 2D image at a point in front of an ultrasonic transducer because of the linearity of ultrasound. Accordingly, existing 1D array ultrasonic probes have problems in that it is difficult to make an accurate diagnosis and it is impossible to contrast a 3D shape of a fetus or a movement of a fetus as a moving image. Recently, there has been a demand for ultrasonic probes that may obtain a 3D image in a human body, in particular, a 3D dynamic image. A 3D image may be obtained by using an existing 1D array ultrasonic probe and or a 2D array ultrasonic probe.
A 2D array ultrasonic probe has problems in that since the 2D array ultrasonic probe includes an extremely larger number of ultrasonic transducers than a 1D array ultrasonic probe, a manufacturing process is complex, and since an image obtained by using the 2D array ultrasonic probe has a low signal-to-noise (S/N) ratio, the quality of the image is low. Accordingly, a method of obtaining a 3D image by using a 1D array ultrasonic probe has recently been continuously studied.
In order to obtain a 3D image by using a 1D array ultrasonic probe, a doctor who makes a diagnosis moves the 1D array ultrasonic probe manually or mechanically. A 1D array ultrasonic probe that obtains a 3D image by being manually manipulated by a doctor who makes a diagnosis has problems in that the quality of an image is very low due to an irregular contrast interval and an error of the 3D image increases according to doctors who make a diagnosis. Accordingly, recently, a method of obtaining a 3D image by mechanically moving a 1D array ultrasonic probe has been actively studied.
Examples of a method of obtaining a 3D image by mechanically moving a 1D array ultrasonic probe may include a method of moving an array axis of ultrasonic transducers in parallel and a method of rotating an array axis of ultrasonic transducers by a predetermined angle. The former method in which an array axis of ultrasonic transducers is moved by using a motor to be parallel to a region of a body to be contrasted has advantages in that a contrast interval of a 3D image is kept uniform and an erroneous occurrence of the 3D image is reduced, but has disadvantages in that since an overall size of an ultrasonic probe including a power generating unit such as the motor is considerably large, it is difficult to manufacture and use the ultrasonic probe.
In contrast, the latter method in which an array axis of ultrasonic transducers is rotated by a predetermined angle over a region of a body to be contrasted along an arc path by using a power generating unit such as a motor has advantages in that since an overall size of an ultrasonic probe is smaller than that of the former method, the usability of the ultrasonic probe is excellent.
Ultrasonic probes that obtain a 3D image by rotating an array axis of ultrasonic transducers may be classified into one-element ultrasonic probes in which a module including ultrasonic transducers and a power generating unit such as a motor are located in a single housing and two-element ultrasonic probes in which a module and a power generating unit are not located in a single housing but are separately located. Two-element ultrasonic probes in which a module and a power generating unit that are not located in the same housing are coupled to each other by a separate element have advantages in that a 2D cross-sectional image may be obtained by using an existing 1D array ultrasonic probe, but have disadvantages in that since the power generating unit is independently located from the module, an overall size of a two-element ultrasonic probe is considerably larger than that of a one-element ultrasonic probe and thus the usability of the two-element ultrasonic probe is low.
In contrast, one-element ultrasonic probes in which a module and a power generating unit are located in the same housing have advantages that since an overall size of a one-element ultrasonic probe is smaller than that of a two-element ultrasonic probe, the ultrasonic probe may be manufactured to have a small size.
However, existing one-element ultrasonic probes have low manufacturability and low durability since a mechanical driving relationship for rotating an array axis of ultrasonic transducers by a predetermined angle is complex. In addition, one-element ultrasonic probes have problems in that although an array axis of ultrasonic transducers has to be rotated by a rotation angle that is as wide as possible in order to obtain an image having better quality, since there is a limitation in the rotation angle due to a wire structure, utilization during diagnosis is reduced, and since an internal structure is complex and air bubbles are stuck at every corner, it is difficult to remove oil. Also, one-element ultrasonic probes have problems in that since a motor and a power transmitting unit that are disposed in a probe occupy a large space, it is difficult to miniaturize the probe, and since additional oil exists in a place where the motor and the power transmitting unit are disposed, it is difficult to lighten the probe. Also, one-element ultrasonic probes have problems in that noise and vibration may occur in a power transmitting unit for transmitting power from a motor.